Device for producing oscillations



March 1949. c. VERBURG ET AL DEVICE FOR PRODUCING OSCILLATIONS Filed April 19, 1946 FIG. 2

. INVENTORS CORNEQJS VERBURG 8 FRANS MICHEL PENNING ATTORNEY.

FIG. 1

Patented Mar. 8, 1949 UNITED STATES PATENT OFFICE DEVICE FOR PRODUCING OSCILLATION S Application April 19, 1946, Serial No. 663,309 In the Netherlands November 27, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires November 27, 1961 2 Claims.

This invention relates to a device for producing preferably ultra high-frequency oscillations and comprising a discharge tube in which is produced an electron beam which is caused to pass successively along a velocity control electrode-system, a device for translating velocity variations into intensity variations and a second and third electrode system, the second electrode system being connected through a back-coupling lead consisting of two conductors, one of which surrounds the other, to the control-electrode system, while energy can be taken from the third electrode system.

Such a device permits the production of oscillations whose frequency is determined by the size of the oscillatory system constituted by the control-electrode system, the second electrodesystem and the back-coupling lead. In fact, the frequency of the produced oscillations is equal to the fundamental frequency of the oscillatory system or a higher harmonic thereof, dependent on the velocity at which the electrons are caused to pass along the electrode systems and consequently on the direct voltages supplied to the two electrode systems.

According to the invention a movable conductor inductively or capacitatively coupled to the control-electrode system is provided in the oscillator system, preferably in the proximity of the control-electrode system or the second electrode system.

The provision of this movable conductor has the advantage that the operation of the device can be acted upon in a simple manner by shifting the conductor. Thus, for instance, a discontinuous frequency variation can be brought about by shifting the conductor, the frequency of a definite natural frequency of the oscillatory system jumping over to another frequency. Furthermore, by shifting the conductor which may be realised in the form of an antenna, the amplitude of the oscillations in the oscillatory system may be adjusted in such manner that the variation of the electron density becomes a maximum at the third electrode system so that a maximum of energy can be abstracted from the third electrode system.

The invention will be more fully explained by reference to the accompanying drawing, given by way of example, in which Fig. 1 is a longitudinal section of one form of construction of a device according to the invention, Fig. 2 being a crosssection on the line IIII of the device represented in Fig. 1.

The device for producing oscillations shown in Fig. 1 consists of a discharge tube comprising an electrode system for producing an electron beam Within an envelope I preferably made of quartz. This electrode system comprises an indirectly heatable cathode 2, a grid 3, an auxiliary anode 4 and an accelerating electrode 5, to which two last-mentioned electrodes is supplied a positive voltage with respect to the cathode. At the end remote from the said electrode system the envelope 1 contains two electrodes 6 and a collecting electrode 1, the latter serving to collect the electrons emitted by the electrode 2. The electrodes 5 and the electrode 1 are also supplied with a positive voltage with respect to the cathode, which voltage in regard to the electrodes 6 preferably corresponds to the positive voltage of the electrode 5 with respect to the cathode and may be lower for the electrode 1, if desired.

In order to prevent deconcentration of the electron beam produced by the electrode system 2, 3, 4, 5 an axially directed magnetic field is preferably provided. The means for producing this field are not illustrated in the drawing.

On the way to the collecting electrode 1 the electrons emitted by the cathode 2 are caused to pass along a least three electrode systems the first of which is the velocity control electrode system consisting of a control electrode 8 and two bounding electrodes 9 and Ill. The bounding electrode I0 is constituted by the end of a drift electrode l I which constitutes a so-called drift space through which the electron beam is passed after having traversed the control electrode system and which serves to translate velocity variations into intensity variations. After that the electron beam is caused to pass along the second electrode system consisting of an electrode I2 and two bounding electrodes I3 and l 4, the latter of which is constituted by the end of the drift electrode H remote from the control-electrode system. The electrodes 8 to M are preferably supplied with a positive voltage with respect to the cathode, which voltage corresponds to the positive voltage of the accelerating electrode 5 relatively to the cathode. For the production of oscillations the second electrode system [2, l3, I4 is connected through a back-coupling lead, consisting of tubular U- shaped preferably co-axial conductors I5 and Hi, to the velocity control electrode system. The third electrode system along which the electron beam is passed consists of an energyabstracting electrode 28 and two bounding electrodes 29 and 30 which form part of an oscillatory system comprising two symmetrically located co-axial transmission lines which consist of the conductors 3|,

32 and 33, 34 respectively and of which the external conductors 3| and 33 are connected to outermost external electrodes 29 and 30, whereas the internal conductors 32 and 34 are connected to the energy-abstracting electrode 28. The effective length of the transmission lines can be controlled by means of pistons 35 and 36 as a result of which the natural frequency of the oscillatory system constituted by the third electrode system 28, 29, 30 and the transmission lines 3|, 32 and 33, 34 in question can be tuned to the frequency of the oscillator system.

The device set out above permits the production of oscillations whose frequency depends on the size of the oscillator system constituted by the electrode system 8, 9, l and I2, l3, l4 and the back-coupling lead I5, I6, the produced oscillation being abstracted from the electrode system 28, 29, 30.

The operation is based on velocity modulation of the electrons in the beam under the action of a control voltage which is supplied to the control electrode 8 of the velocity control electrode system and translation of the velocity variations thus obtained into intensity variations in the so-called drift space, which intensity variations produce an oscillation in the oscillatory system, of which the second electrode system forms part, which oscillation is supplied through the back-coupling lead to the Velocity control electrode system and acts as a control voltage.

By the electron beam, whose intensity varies in the rhythm of the oscillations produced by means of the oscillator system oscillations are produced, on traversing the third electrode system 28, 28, 30, in the oscillatory system connected to the lastmentioned system.

As a rule the oscillator system has a number of natural frequencies whose appearance or not will depend on the choice of the applied voltages. However, there are other ranges of voltages within which the production of two or more frequencies is possible. In order that a definite desired frequency may be produced in these ranges a movable conductor 26 is provided according to the invention, as shown in Fig. 2, which is located in the vicinity of the second electrode system I2, it, it and capacitatively coupled to the electrode E2 of this system. It now appears to be possible, by adjustment of the coupling between the conductor 29 and the electrode l 2, to vary the frequency of the produced oscillations in a discontinuous manner and consequently to select'in this way a definite frequency from a number of possible natural frequencies of the oscillator system.

Moreover, by varying the said coupling at a definite frequency, as a result of which, for instance, when utilizing the conductor as an antenna, a variable quantity of energy is abstracted from the oscillator system, the amplitude of the oscillations produced in the oscillator system can be varied which permits the device to be adjusted to a maximum output of the energy abstracted in the third electrode system.

We claim:

1. A device for generating oscillations comprising, an electron discharge tube having means to generate an electron beam, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member coupled to said assemblies, said velocity control and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said assemblies and said member being mounted along the path of said electron beam, a transmission line coupling said velocity-control electrode assembly to said second electrode assembly, said transmission line comprising a tubular conductor and another conductor within said tubular conductor, and means comprising an adjustable conductor coupled in capacitive relationship to the central electrode of one of said electrode assemblies to vary discontinuously the frequency of the generated oscillations.

2. A device for generating oscillations comprising an electron discharge tube having an envelope and a heatable cathode, a grid, an auxiliary anode, an accelerating electrode, a further electrode and a collector electrode within said envelope, a velocity-control electrode assembly, a second electrode assembly, a drift electrode member interposed between and coupling said velocity-control electrode and said second electrode assemblies, a third electrode assembly, said velocitycontrol and second electrode assemblies each comprising a bounding electrode, an end portion of said drift electrode member and a central electrode interposed between said bounding electrode and the respective end portion of said drift electrode member, said third electrode assembly comprising two bounding electrodes and a central electrode interposed therebetween, said assemblies and said member being mounted along the comprising a tubular conductor and another conductor within said tubular conductor, an adjustable conductor connected to the outer conductor of said concentric transmission line and capacitively coupled to the central electrode of said second electrode assembly, thereby selectively to vary discontinuously the frequency of the generated oscillations, first and second coaxial transmission lines coupled to and symmetrically mounted with respect to said third electrode assembly, each of said coaxial transmission lines having an adjustable annular conducting member interposed between the inner and outer conductors thereof to vary the effective length and having the inner conductor thereof coupled to the central electrode and the outer conductor thereof coupled to said bounding electrodes of said third electrode assembly, thereby to vary the frequency of the oscillations produced in said third electrode assembly, and an output deriving means coupled to said third electrode assembly.

CORNELIS VERBURG.

FRANS MICHEL PENNING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,222,902 Hahn Nov. 26, 1940 2,280,824 Hensen et al Apr. 28, 1942 2,281,935 Hansen et al May 5, 1942 

